Wash the bok choy and cut the stalks and leaves into 2 inch (5 cm) sections.
Cut the large abalone mushrooms into smaller pieces.
Save the liquid for later use.
Heat the oil in the wok.
Add the bok choy gradually and stir fry until it is thoroughly coated with oil.
Add the mushrooms, salt, sugar, the liquid from the mushroom can, and 1/2 cup chicken broth.
Cover and simmer for about 4 to 5 minutes.
Give the tapioca starch mixture a quick stir before pouring it into the wok.
Stir fry a few seconds until the sauce thickens.